1. Field of the Invention
This invention relates to a pacing unit, and more particularly to a cardiac pace maker.
2. Description of the Prior Art
A cardiac pace maker (referred to as a pacer which it is also called so, hereinafter) is an electric device used when arrhythmias occur, to control the heart's rhythm and maintain the normal action of the heart. The pacer, by watching the progress of the heart's action potential wave, can detect an abnormal wave if it occurs, and responds to it by restoring the heart's normal rhythm.
For example, as illustrated in FIG. 10, a pacing catheter 1 with two spaced electrodes 3, 23 at the end is inserted through the vena cava 6 into the heart 7, passing through the right atrium 8 into the right ventricle 9, to at last reach the ventricular apex 9a. The electrodes 3, 23, which thus are positioned at the ventricular apex portion 9a, pick up continuously the action potential of the heart and transmit them via leads 15, 16 running through the catheter lumen to a pacer 5. Upon sensing the absence of the action potential which should be detected at a specified time, immediately the pacer 5 signals via the leads 15, 16 to electrodes 3, 23 which electrically stimulate the heart to pulsate. In FIG. 10, reference characters 10 and 11 designate the left atrium and the left ventricle, respectively.
The pacing unit is constructed of the external pacer 5 disposed apart from the patient's body and the catheter 1 of which the distal end portion is inserted into the heart 7 as stated above. At the proximal end, leads 15, 16 extend out, their connector-plug ends being plugged in the pacer 5. Such construction presents a hazard that the connector plugs can be pulled off the pacer 5, for example, when the patient moves. The pacer 5 itself is usually heavy and large in size (for example, 18 cm long, 8 cm wide and 5 cm high). This may also contribute to the connector plugs being pulled off.
The above-described deficiency reflects, as a potential hazard of medical treatment, a lower reliability of pacing.